1. Field of the Invention
The present invention relates to an electric double layer capacitor with improved structure for receiving a separator and polarizable electrodes.
2. Description of the Related Art
Japanese Patent Publication No. 9337/1985 discloses a prior art electric double layer capacitor 1 having the structure as shown in FIG. 9. The electric double layer capacitor 1 comprises a gasket 2 of insulating rubber and a separator 3 and polarizable electrodes 4 and 5 received in an opening 2a of the gasket 2. The polarizable electrodes 4 and 5 are made of solid carbonaceous material, and arranged to be opposite to each other on both sides of the separator 3. The separator 3 is made of electrically insulative material having ion permeability.
The separator 3 and the polarizable electrodes 4 and 5 are impregnated with an electrolyte such as 30% sulfuric acid and received in the opening 2a of the gasket 2, to which collecting electrodes 6 and 7 are adhered by a rubber-system, epoxy-system or hot melting-system adhesive agent to seal the opening 2a.
As hereinabove described, the polarizable electrodes 4 and 5 are opposite to each other on opposite side of the separator 3 and sealed in the opening 2a by the collecting electrodes 6 and 7. Therefore, the polarizable electrodes 4 and 5 are liable to be displaced in the opening 2a and may, for example, come into contact with one peripheral edge of the opening 2a as shown in FIG. 10. If a clearance or gap exists between the separator 3 and the peripheral edge of the opening 2a, the polarizable electrodes 4 and 5, which must be separated from each other, may come into contact with each other as shown in FIG. 10 to cause shorting. Such shorting occurs at a rate of about 30% in the manufacturing process of conventional electric double layer capacitors 1, resulting in extremely inferior production yield.
Even if no such shorting is observed in the inspection process upon manufacturing, the polarizable electrodes 4 and 5 may be displaced in transportation or in use to cause shorting. Thus, awaited is an electric double layer capacitor or higher reliability.